Differentiating scleroderma renal crisis from other causes of thrombotic microangiopathy in a postpartum patient

Thrombotic thrombocytopenic purpura (TTP), hemolytic uremic syndrome (HUS), and scleroderma renal crisis (SRC) all present with features of thrombotic microangiopathy. Distinguishing among these entities is critical, however, as treatments differ and may be mutually exclusive. We describe the case of a 25-year-old woman with an undefined mixed connective tissue disease who presented 6 weeks post-partum with fever, transient aphasia, thrombocytopenia, hemolytic anemia, and acute kidney injury eventually requiring initiation of hemodialysis. Renal biopsy revealed thrombotic microangiopathy. Renal function did not improve despite immediate initiation of plasma exchange, and an angiotensin-converting enzyme (ACE) inhibitor was initiated following discontinuation of plasma exchange. At last follow up, she remained dialysis dependent. Due to the myriad causes of thrombotic microangiopathy and potential for diagnostic uncertainty, the patient's response to therapy should be closely monitored and used to guide modification of therapy.